In a large dutch oven, combine chicken broth, potatoes, carrots, celery, onion, parsley flakes, and frozen corn. Bring to a boil and cook until vegetables are tender.
In a separate bowl, combine flour, cornstarch, and 2 cups of half and half. Stir slurry into cooked vegetable mixture.
In a separate saucepan over medium, heat remaining 4 cups of half and half. Stir in Velveeta and shredded cheddar cheese. Stir continuously until cheese are melted.
When cheese is melted add to cooked vegetable mixture. Stir to combine.
Add ham and diced bacon to soup. Salt and pepper soup to taste.
Notes: This soup fills one large crockpot or slow cooker. Doubling this recipe to feed a crowd will fit into a medium sized roaster with plenty of room to stir.